Added plugin `detectindent.lua`

2 files changed, 65 insertions, 0 deletions

diff --git a/README.md b/README.md
index 17fc1e8..57bc5a4 100644
--- a/README.md
+++ b/README.md
@@ -13,6 +13,7 @@ Plugin | Description
 [`autowrap`](plugins/autowrap.lua?raw=1) | Automatically hardwraps lines when typing
 [`bracketmatch`](plugins/bracketmatch.lua?raw=1) | Underlines matching right-bracket of left-bracket under caret *([screenshot](https://user-images.githubusercontent.com/3920290/80132745-0c863f00-8594-11ea-8875-c455c6fd7eae.png))*
 [`colorpreview`](plugins/colorpreview.lua?raw=1) | Underlays color values (eg. `#ff00ff` or `rgb(255, 0, 255)`) with their resultant color. *([screenshot](https://user-images.githubusercontent.com/3920290/80743752-731bd780-8b15-11ea-97d3-847db927c5dc.png))*
+[`detectindent`](plugins/detectindent.lua?raw=1) | Automatically detects and uses the indentation size and tab type of a loaded file
 [`drawwhitespace`](plugins/drawwhitespace.lua?raw=1) | Draws tabs and spaces *([screenshot](https://user-images.githubusercontent.com/3920290/80573013-22ae5800-89f7-11ea-9895-6362a1c0abc7.png))*
 [`eval`](plugins/eval.lua?raw=1) | Replaces selected Lua code with its evaluated result
 [`gofmt`](plugins/gofmt.lua?raw=1) | Auto-formats the current go file, adds the missing imports and the missing return cases
diff --git a/plugins/detectindent.lua b/plugins/detectindent.lua
new file mode 100644
index 0000000..9c473b5
--- /dev/null
+++ b/plugins/detectindent.lua
@@ -0,0 +1,64 @@
+local core = require "core"
+local command = require "core.command"
+local config = require "core.config"
+local DocView = require "core.docview"
+local Doc = require "core.doc"
+
+local cache = setmetatable({}, { __mode = "k" })
+
+
+local function detect_indent(doc)
+  for _, text in ipairs(doc.lines) do
+    local str = text:match("^  +")
+    if str then return "soft", #str end
+    local str = text:match("^\t+")
+    if str then return "hard" end
+  end
+end
+
+
+local function update_cache(doc)
+  local type, size = detect_indent(doc)
+  if type then
+    cache[doc] = { type = type, size = size }
+  end
+end
+
+
+local new = Doc.new
+function Doc:new(...)
+  new(self, ...)
+  update_cache(self)
+end
+
+local clean = Doc.clean
+function Doc:clean(...)
+  clean(self, ...)
+  update_cache(self)
+end
+
+
+local function with_indent_override(doc, fn, ...)
+  local c = cache[doc]
+  if not c then
+    return fn(...)
+  end
+  local type, size = config.tab_type, config.indent_size
+  config.tab_type, config.indent_size = c.type, c.size or config.indent_size
+  local r1, r2, r3 = fn(...)
+  config.tab_type, config.indent_size = type, size
+  return r1, r2, r3
+end
+
+
+local perform = command.perform
+function command.perform(...)
+  return with_indent_override(core.active_view.doc, perform, ...)
+end
+
+
+local draw = DocView.draw
+function DocView:draw(...)
+  return with_indent_override(self.doc, draw, self, ...)
+end
+